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The formation of a peptide bond requires an input of energy. The two reacting molecules are the alpha amino group of one amino acid and the alpha carboxyl group of the other amino acids. A by-product of this bond formation is the release of water (the amino group donates a proton while the carboxyl group donates a hydroxyl). [2]
Proteolysis in organisms serves many purposes; for example, digestive enzymes break down proteins in food to provide amino acids for the organism, while proteolytic processing of a polypeptide chain after its synthesis may be necessary for the production of an active protein.
A representation of the 3D structure of the protein myoglobin showing turquoise α-helices. This protein was the first to have its structure solved by X-ray crystallography. Toward the right-center among the coils, a prosthetic group called a heme group (shown in gray) with a bound oxygen molecule (red).
Transformed functional groups after each chemical reaction are highlighted in red. Amino acids, including tryptophan, are used as building blocks in protein biosynthesis, and proteins are required to sustain life. Tryptophan is among the less common amino acids found in proteins, but it plays important structural or functional roles whenever it ...
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism. Proteins are the major source of nitrogen in food. BV assumes protein is the only ...
This value is known as the "crude protein" content. The use of correct conversion factors is heavily debated, specifically with the introduction of more plant-derived protein products. [20] However, on food labels the protein is calculated by the nitrogen multiplied by 6.25, because the average nitrogen content of proteins is about 16%.
By understanding glycoproteins and their synthesis, they can be made to treat cancer, Crohn's Disease, high cholesterol, and more. [3] The process of glycosylation (binding a carbohydrate to a protein) is a post-translational modification, meaning it happens after the production of the protein. [3]
During the synthesis of proteins, polypeptide chains, which are created by ribosomes translating mRNA, must be processed before assuming a mature conformation. The dephosphorylation of proteins is a mechanism for modifying behavior of a protein, often by activating or inactivating an enzyme .